View Full Version : Velocity seems too high
Iwsbull
07-26-2019, 11:27 PM
I loaded some 429421 pc boolits over 8.5 grains of unique and the velocity was a good bit higher than I was expecting. 1052 with a 10 shot string mixed head stamp brass and a sd of 11. This is out of a 7 1/2” Super Redhawk. Well above what my Lyman book said. Have y’all ran into this before? I seared to the crimp ring.
Wheelguns 1961
07-26-2019, 11:39 PM
First thing. What was the test firearm? There are many factors that affect velocity in a revolver, including B/C gap, barrel uniformity and smoothness, etc. I know that in my cast bullet handbook, the test firearm is a 4” universal receiver. I am not an expert, but this is not unusual.
bmortell
07-26-2019, 11:42 PM
my notes: 6.5" SBH 240swc 10.5gr unique 1160fps, 11.5gr 1220fps.
lyman is a bit like that
Larry Gibson
07-26-2019, 11:57 PM
Lyman uses a 4" test barrel for their 44 magnum velocities.
Iwsbull
07-27-2019, 12:02 AM
It just kinda puzzled me that Lyman listed a starting load of 9.8 at 912 FPS and being close to 1 1/2 grains lower I had much better velocity. I guess as fast as unique is I was not expecting the extra barrel length to make that much difference. I will say that the 8.5 load was mighty accurate and it may become my all around load from plinking to deer and hogs.
Groo here
Also remrember lead boolets are faster than jacket [often 100 fps in heaver loads] due to the
hardness of the jacket...
kingrj
07-27-2019, 08:41 AM
This seems perfectly normal data to me....
Larry Gibson
07-27-2019, 09:44 AM
255 gr RCBS 44-250-K over 8.5 gr Unique in W-W cases with WLP primer; 4" Colt Anaconda ran 930 fps, 6 1/2" Ruger FTBH ran 1010 fps.
My standard 44 Magnum load for general use these days is this 8.5 gr load with a 240 - 260 gr bullet (my own cast or commercial). Recently acquired a 4 cavity Lyman 429421 mould (from Lloyd....thanks again) and will be casting some bullets with it shortly. They will be loaded over 8.5 gr Unique.......
RED BEAR
07-27-2019, 10:59 AM
Lyman uses a 4" test barrel for their 44 magnum velocities.
Well this solves it .
onelight
07-27-2019, 11:17 AM
There is a good article in the Speer #9 manual on page 348 “Why ballisticians get gray” they checked the same loads through a lot of different guns with different results.
Good article if you have that manual .
georgerkahn
07-27-2019, 01:25 PM
I shot same bullet over 8.0 gns Unique, CCI regular primer, mixed brass in a "Dirty Harry" 6.5" Smith, and fellow at range chronied them at an average (six shots, ea) of 912fps, and 940fps, respectively. If I had similar results as yours, out of a 7 1/2" bbl Redhawk, I'd not at all be too concerned. Bion, I have noted chrony set-up and brand do make a difference, too. Mine is an Oehler 35p; fellow at range had a PACT. Regardless, you use a one-half grain more of same powder, and gain a tad more velocity -- apparently velocity and powder charge is not a linear function -- so again, I'd not be too alarmed.
geo
Don Purcell
07-27-2019, 01:31 PM
Out of a 7 1/2 inch barrel your load is spot on. Run with it and have some easy efficient fun.
Outpost75
07-27-2019, 02:00 PM
Also consider that differences in barrel-cylinder gap affect velocity.
A short-barrrel revolver set up to minimum factory tolerance (pass 0.002/hold 0.003") may produce higher velocity than a longer-barrel revolver having a wider gap greater than Mean Assembly tolerance (pass 0.005/hold 0.06) and will certainly be faster than a loose gun at Customer Service Maximum (pass 0.008/hold 0.009).
Those were Ruger specs the factory built to in the 1980s. I have recently observed new guns of both S&W and Ruger manufacture with huge B/C gaps which wouldn't have been allowed to ship in my time...
onelight
07-27-2019, 07:49 PM
Also consider that differences in barrel-cylinder gap affect velocity.
A short-barrrel revolver set up to minimum factory tolerance (pass 0.002/hold 0.003") may produce higher velocity than a longer-barrel revolver having a wider gap greater than Mean Assembly tolerance (pass 0.005/hold 0.06) and will certainly be faster than a loose gun at Customer Service Maximum (pass 0.008/hold 0.009).
Those were Ruger specs the factory built to in the 1980s. I have recently observed new guns of both S&W and Ruger manufacture with huge B/C gaps which wouldn't have been allowed to ship in my time...
A shooting buddy just got a new gp100 it was .0015 to tight .
Outpost75
07-27-2019, 09:06 PM
A shooting buddy just got a new gp100 it was .0015 to tight .
MUCH easier to deal with than loosey-goosey, when you must either set the barrel back or refit a different cylinder! But at 0.0015 a gun my bind when it gets hot, or with just a bit of lead fouling.
If you have the Brownell's facing cutter, bushings and T-handle, a simple fix.
onelight
07-27-2019, 09:40 PM
I found part of the article from the. Speer manual
http://www.leverguns.com/articles/ballisticians.htm
rintinglen
07-28-2019, 11:39 AM
A "snug" barrel with a tight barrel cylinder gap can markedly elevate pressures and consequently velocities. My old buddy Rick had a 5 1/2 inch Redhawk that had a narrow BC gap ~.003 and a .4285 groove diameter barrel. It ran 75 fps faster than my 7 1/2 incher with identical loads.
onelight
07-28-2019, 03:54 PM
MUCH easier to deal with than loosey-goosey, when you must either set the barrel back or refit a different cylinder! But at 0.0015 a gun my bind when it gets hot, or with just a bit of lead fouling.
If you have the Brownell's facing cutter, bushings and T-handle, a simple fix.
It’s new so Ruger would fix it I’m sure , it will only be a range gun and he wants to shoot as is but it does not take much to bind it up. He is also learning a Dillon 550 he just got and had few high primers just barely high and they put it in a bind. He is a retired detective and has loaded and shot for many years so he knows the situation and gonna see if it will loosen up with some range time.
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